The present invention disclosed herein relates to a substrate processing apparatus, and more particularly, to a substrate processing apparatus and a method for transferring a substrate for the substrate processing apparatus.
In a substrate manufacturing method, processes such as deposition of dielectric films and metallic materials, etching, coating with photoresist, developing, and removing of asher are repeated for a predetermined number of times so as to forming arrays of fine patterns. Although an etching or asher-removing process is performed during such substrate manufacturing processes, foreign substances are not completely removed from a substrate but remain on the substrate. For this reason, a wet cleaning process may be performed using deionized water or chemicals so as to remove such remaining substances.
Substrate cleaning apparatuses for wet cleaning may be classified into batch processors and single processors. A batch processor may include a chemical bath, a rinse bath, and a dry bath that are sized to process about 25 to 50 substrates at a time. In a batch processor, substrates are immersed in each bath for a predetermined time for removing foreign substances from the substrates. In such a batch processor, both the front and rear sides of a large number of substrates can be simultaneously processed. However, since the sizes of baths of a batch process are proportional to the size of substrates, the size and chemical consumption of the batch processor increase as the size of substrates increases. Moreover, when a substrate is cleaned in a chemical bath, foreign substances detached from a neighboring substrate can be re-attached to the substrate.
Since the sizes of recently-used substrates are large, single processors are widely used. In the case of a single processor, a substrate cleaning process is performed in a relatively small chamber capable of processing only a single substrate at a time. Specifically, in a single processor, a substrate is fixed to a chuck disposed in a chamber, and a chemical or deionized water is supplied to the top surface of the substrate through a nozzle while rotating the substrate using a motor. Since the substrate is rotated, the chemical or deionized water can spread on the substrate, and foreign substances are removed from the substrate by the spreading chemical or deionized water. Such a single processor is relatively small and suitable for uniformly cleaning a substrate as compared with a batch processor.
Generally, a single processor includes a plurality of load ports, an index robot, a buffer unit, a plurality of process chambers, and a main transfer robot that are arranged from a side of the single processor. Front opening unified pods (FOUPs) accommodating substrates are placed on the load ports, respectively. The index robot carries the substrates accommodated in the FOUP to the buffer unit, and the main transfer robot transfers the substrates from the buffer unit to the process chambers. After the substrates are cleaned in the process chambers, the main transfer robot carries the substrates from the process chambers to the buffer unit, and the index robot takes the substrates from the buffer unit and puts the substrates into the FOUP. After the cleaned substrates are accommodated in the FOUP as described, the FOUP is carried to the outside.
Generally, a FOUP is transferred by an overhead hoist transport (OHT). In detail, the OHT transfers a FOUP accommodating uncleaned substrates to an empty load port, and the OHT picks up a FOUP accommodating cleaned substrates from the load port and transfers the FOUP to an outside area.
Since such an OHT is operated with a low speed, it takes more time to transfer a FOUP using the OHT than to draw uncleaned substrates from the FOUP and put cleaned substrates into the FOUP. Moreover, the time necessary for cleaning substrates is shortened because the efficiency of a cleaning apparatus is improved owing to the development of related technology; however, the speed of OHTs is still low. Therefore, FOUPs cannot be efficiently transferred by using an OHT, thereby increasing the idle time of a cleaning apparatus and decreasing the productivity of a manufacturing process.